Collector mirror exchanging apparatus and method for extreme ultraviolet light source apparatus

ABSTRACT

A collector mirror exchanging apparatus capable of safely and easily exchanging a collector mirror for collecting extreme ultra violet light emitted from plasma generated within a chamber of an extreme ultra violet light source apparatus. The collector mirror exchanging apparatus includes: a supporting base for supporting a collector mirror or a collector mirror structure; and a guiding rail disposed on the supporting base and regulating a moving direction of the collector mirror or the collector mirror structure; wherein at least the collector mirror is taken out of the chamber by moving the collector mirror or the collector mirror structure along the guiding rail on the supporting base.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a collector mirror exchanging apparatusand a collector mirror exchanging method to be used to exchange acollector mirror for collecting extreme ultra violet (EUV) light emittedfrom plasma in an extreme ultra violet light source apparatus.

2. Description of a Related Art

Recent years, as semiconductor processes become finer, photolithographyhas been making rapid progress to finer fabrication. In the nextgeneration, microfabrication of 100 nm to 70 nm, further,microfabrication of 50 nm or less will be required. Accordingly, inorder to fulfill the requirement for microfabrication of 50 nm or less,for example, exposure equipment is expected to be developed by combiningan EUV light source generating EUV light with a wavelength of about 13nm and reduced projection reflective optics.

As the EUV light source, there are three kinds of light sources, whichinclude an LPP (laser produced plasma) light source using plasmagenerated by applying a laser beam to a target (hereinafter, alsoreferred to as “LPP type EUV light source apparatus”), a DPP (dischargeproduced plasma) light source using plasma generated by discharge, andan SR (synchrotron radiation) light source using orbital radiation.Among them, the LPP light source has advantages that extremely highintensity close to black body radiation can be obtained because plasmadensity can be considerably made larger, that light emission of only thenecessary waveband can be performed by selecting the target material,and that an extremely large collection solid angle of 2π steradian canbe ensured because it is a point light source having substantiallyisotropic angle distribution and there is no structure surrounding thelight source such as electrodes. Therefore, the LPP light source isthought to be predominant as a light source for EUV lithographyrequiring power of several tens of watts.

For example, EUV light is generated in the LPP type EUV light sourceapparatus under a principle as follows. That is, a target material issupplied into a vacuum chamber by use of a nozzle, and this targetmaterial is irradiated with a laser beam to be excited and turned intoplasma. Light with various wavelengths including extreme ultra violet(EUV) light is emitted from plasma thus generated. Then, the EUV lightis reflected and collected to be emitted to an exposure unit by use of acollector mirror (light collecting mirror) which selectively reflectslight with a desired wavelength (13.5 nm, for example) therein.

As a collector mirror for collecting EUV light with a wave length near13.5 nm, for example, there is used a mirror having a reflecting surfaceon which thin films of molybdenum (Mo) and silicon (Si) are alternatelydeposited. Typically, the number of the deposited layers of the Mo/Sithin film ranges up to several hundred. Also, smoothness and a shape ofthe reflecting surface of the collector mirror should be controlled withan extreme preciseness, in order to increase a collecting efficiency ofthe EUV light. Therefore, the collector mirror is extremely expensive.

Further, the collector mirror is easily damaged by flying particles suchas high speed ions and neutrons emitted from a target material turnedinto plasma. Therefore, the collector mirror is disposed as far aspossible from a plasma generating point (light emitting point). Also, acollecting solid angle of the collecting mirror should be made largerfor increasing output power of the EUV light, and therefore, thecollector mirror becomes inevitably larger in radius and accordinglybecomes heavy.

By the way, exchange of such a collector mirror is performed manually.However, it is considerably troublesome to exchange a heavy collectormirror and, if the operation failed, the failure probably would lead toa breakage of the collector mirror and an injury of an operator. Sincethe collector mirror is extremely expensive, resulting damage thereof isconsiderable. Therefore, a method of exchanging collector mirrors safelyand easily is desired.

As a relating technology, Japanese Patent Application PublicationJP-P2004-103961A discloses a mirror holding unit including a mirror andan elastic member for elastically coupling the mirror to a hatch whichis openably provided on a wall of a chamber capable of generatingreduced-pressure environment, in order to make it easy to exchange anilluminating optical system and keep an initial alignment accuracy, andfurther make short a time required for the exchange to improve exposurethroughput.

In JP-P2004-103961A, however, weights of the collector mirror, the hatchof the chamber to which the mirror is attached, and the supportingmember (elastic member) for coupling the mirror to the hatch are nottaken into consideration. That is, although a heavy weight should besupported when fixing these parts to the wall of the chamber, no meansfor supporting the heavy weight is disclosed.

SUMMARY OF THE INVENTION

The present invention has been achieved in view of these problems. Anobject of the present invention is to provide an apparatus and a methodof safely and easily exchanging a collector mirror for collecting EUVlight in an EUV light source apparatus.

For achieving the object, a collector mirror exchanging apparatusaccording to one aspect of the present invention is an apparatus to beused for exchanging a collector mirror, which reflects and collectsextreme ultra violet light emitted from plasma generated in a chamber ofan extreme ultra violet light source apparatus, and includes: asupporting base which supports a collector mirror or a collector mirrorstructure including the collector mirror; and guiding means disposed onthe supporting base and regulating a moving direction of the collectormirror or the collector mirror structure; wherein at least the collectormirror is taken out of the chamber by moving the collector mirror or thecollector mirror structure along the guiding means on the supportingbase.

Also, a collector mirror exchanging method according to one aspect ofthe present invention is a method of exchanging a collector mirror,which reflects and collects extreme ultra violet light emitted fromplasma generated in a chamber of an extreme ultra violet light sourceapparatus, and includes the steps of: (a) moving a collector mirror or acollector mirror structure including the collector mirror whileregulating a moving direction thereof along guiding means disposed on asupporting base, to take at least the collector mirror out of thechamber; (b) exchanging a used collector mirror for a new collectormirror outside the chamber; and (c) moving the collector mirror afterexchange or the collector mirror structure including the mirror afterexchange while regulating a moving direction thereof along the guidingmeans disposed on the supporting base, to return at least the collectormirror to a former position thereof.

According to the present invention, a collector mirror or a collectormirror structure integrating the collector mirror and a mechanismtherearound is moved on a supporting base while a moving directionthereof is being regulated, and thereby, the collector mirror isexchanged after having been taken out of a chamber. Therefore, acollector mirror can be exchanged safely and with a high accuracy in ashort time, even if the collector mirror or the structure has aheavyweight. As a result, trouble in exchanging the collector mirror canbe reduced and an accident of breaking a collector mirror or an injurythereby is prevented from occurring, and a line operating rate can beimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram showing a part of an extreme ultraviolet light source apparatus including a collector mirror exchangingapparatus according to a first embodiment of the present invention;

FIG. 2 is an enlarged side view showing a collector mirror unit shown inFIG. 1;

FIG. 3 is a plan view showing the collector mirror unit shown in FIG. 1;

FIG. 4 is a side view showing a collector mirror exchanging apparatusaccording to a second embodiment of the present invention;

FIG. 5 is a side view showing an appearance in which a collector mirrorunit is reversed in the collector mirror exchanging apparatus accordingto the second embodiment of the present invention;

FIG. 6 is a side view showing a collector mirror exchanging apparatusaccording to a third embodiment of the present invention;

FIG. 7 is a side view showing an appearance in which a collector mirroris rotated in the collector mirror exchanging apparatus according to thethird embodiment of the present invention;

FIGS. 8A and 8B are diagrams showing parts of an extreme ultra violetlight source apparatus including a collector mirror exchanging apparatusaccording to a fourth embodiment of the present invention;

FIG. 9 is a plan view showing a part of the extreme ultra violet lightsource apparatus including the collector mirror exchanging apparatusaccording to the fourth embodiment of the present invention;

FIG. 10 is a plan view illustrating a collector mirror exchanging methodaccording to the fourth embodiment of the present invention;

FIG. 11 is a plan view illustrating the collector mirror exchangingmethod according to the fourth embodiment of the present invention;

FIG. 12 is a plan view illustrating the collector mirror exchangingmethod according to the fourth embodiment of the present invention;

FIG. 13 is a plan view illustrating the collector mirror exchangingmethod according to the fourth embodiment of the present invention;

FIG. 14 is a plan view illustrating the collector mirror exchangingmethod according to the fourth embodiment of the present invention;

FIG. 15 is a plan view showing a part of an extreme ultra violet lightsource apparatus including a collector mirror exchanging apparatusaccording to a fifth embodiment of the present invention;

FIG. 16 is a side view showing a part of an extreme ultra violet lightsource apparatus including a collector mirror exchanging apparatusaccording to a sixth embodiment of the present invention;

FIG. 17 is a side view illustrating a collector mirror exchanging methodaccording to the sixth embodiment of the present invention; and

FIG. 18 is a side view illustrating the collector mirror exchangingmethod according to the sixth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings. The same constituent element willbe denoted by the same reference numeral and description thereof will beomitted.

FIG. 1 is a perspective view showing a part of an extreme ultra violet(EUV) light source apparatus including a collector mirror exchangingapparatus according to a first embodiment of the present invention. ThisEUV light source apparatus includes a target nozzle 110, a laseroscillator 120, a collector mirror unit 130, an EUV filter 140, a targetcollecting unit 150, and a collector mirror exchanging apparatus 160.These units except for the laser oscillator 120 are disposed within achamber provided with a vacuum exhausting unit.

The target nozzle 110 ejects a target material 1 supplied from outsidethe chamber and forms a target jet or a droplet target to be supplied toa plasma generating point (position where plasma is generated byirradiation of the target material 1 with a laser beam 2). In the caseof forming the droplet target, there is further provided a vibratingmechanism which vibrates the target nozzle 110 for forming a target jetat a predetermined frequency.

The laser oscillator 120 is a laser light source which canpulse-oscillate at a high repetition frequency, and outputs the laserbeam 2 for exciting the target material 1 by irradiation thereof. Also,a collective lens 121 is disposed on a light path of the laseroscillator 120, and thereby, a laser beam 2 output from the laseroscillator 120 is focused onto the plasma generating point. Although acollective lens 121 is used in FIG. 1, a light collecting system may beconstituted with another light collecting optical component or acombination of multiple optical components.

FIG. 2 is an enlarged side view showing the collector mirror unit 130shown in FIG. 1. The collector mirror unit 130 is a collector mirrorstructure including a collector mirror 10 which reflects and collectsEUV light emitted from plasma, and mechanisms 12 to 40 for maintaining afunction of the collector mirror 10. In the present application, eitheronly the collector may be exchanged or the whole collector structure maybe exchanged, in exchanging the collector mirror.

The collector mirror unit 130 includes a collector mirror 10, acollector mirror fixing unit 12, a cooling unit 20, a collector mirrorrotating unit 30, and a supporting part 40.

The collector mirror 10 has a reflecting surface 11 which reflectsselectively EUV light with a predetermined wavelength (13.5 nm, forexample) to be focused on a predetermined position. On this reflectingsurface 11, there is formed a Mo/Si multi-layered film alternatelylayered with a molybdenum (Mo) film and a silicon (Si) film, forexample. Such a collector mirror 10 is supported by the collector mirrorfixing unit 12.

The cooling unit 20 is provided at the rear side of the collector mirror10 and prevents temperature of the collecting mirror 10 from increasingby heat generated from plasma. In the cooling unit 20, a pipe 21 forintroducing coolant like water into the cooling unit 20 and another pipe22 for discharging the coolant from the cooling unit 20 are provided,and within the cooling unit 20, a flow path 23 is formed for circulatingthe coolant. The pipes 21 and 22 are formed with a flexible material foraccommodating an operation to rotate or exchange the collector mirror10.

The rotating unit 30 rotates the collector mirror 10 circumferentially,when a part of the reflecting surface of collector mirror 10 is damagedby ions or the like flying from plasma, to reduce an influence of anarea damaged in reflectance of EUV light emitted from plasma. Therotating unit 30 employs a worm gear structure including such as acylindrical worm and a worm wheel. Here, the worm gear structure is amechanism in which both teeth of a cylindrical worm (screw gear) and aworm wheel (slanted teeth gear) are brought into mesh and the worm wheelis rotated by driving the cylindrical worm to rotate.

Each of these units 10 to 30 is supported by the supporting part 40.

Hereinafter, a direction in which the collector mirror 10 faces afocusing point is referred to as a forward direction of the collectormirror unit 130, and a reverse direction thereof is referred to as abackward direction of the collector mirror unit 130.

Referring to FIG. 1 again, plasma is generated by irradiating the targetmaterial 1 ejected from the target nozzle 110 with a laser beam 2, andlight with various wavelengths is emitted therefrom. A light componentwith a predetermined wavelength (13.5 nm, for example) of this light isreflected and collected by a collector mirror 10. The EUV light 3 isoutput to an exposure unit, for example, via the EUV filter 140 disposedat a focusing point of the collector mirror 10 and via an output opticalsystem in the following stage. Here, the EUV filter 140 is a filter forselectively transmitting a light component with a predeterminedwavelength (13.5 nm, for example) and for preventing a light componentwith unnecessary wavelengths from entering into a side of the exposureunit.

The target collecting unit 150 collects target material which wasejected from the target nozzle 110 and has not been irradiated with alaser beam 2 and has not contribute to the generation of EUV light 3.

The collector mirror exchanging apparatus 160 includes a collectormirror supporting base 161 which mounts the collector mirror unit 130, amirror exchanging rail 162 disposed on the collector mirror supportingbase 161, a position adjusting stage 163, an alignment pin 164, and analignment fixing unit (not shown in the drawing).

The mirror exchanging rail 162 is used as a guide for regulating amoving direction of the collector mirror unit 130, when the collectormirror unit 130 is taken out of the chamber in a mirror exchangingoperation. The alignment pin 164 is disposed at a front end of themirror exchanging rail 162, and the collector mirror unit 130 is moveduntil striking this position to obtain a positional accuracy.

The position adjusting stage 163 includes an XYZ stage which can move inthe three-dimensional directions, a stage which can rotate in thehorizontal plane and a stage which can rotate in a direction ofelevation angles, and adjusts a position and posture of the collectormirror unit 130.

The alignment fixing device is provided on the collector mirrorsupporting base 161 for fixing a position of the collector mirror unit130 after the position thereof have been adjusted. That is, when thealignment fixing unit is locked, a position of the collector mirror unitis fixed, and when the lock is released, a position of the collectormirror unit is allowed to be moved.

In the present embodiment, the collector mirror 10 is exchanged asfollows. First, lock of the alignment fixing device is released and thecollector mirror unit 130 is moved along the mirror exchanging rail 162to the backward direction of the collector mirror 10 (in the leftdirection in the drawing) to be taken out from the chamber. Then,outside the chamber, a collector mirror 10 in the collector mirror unit130 is exchanged for a new one, and the collector mirror unit 130 afterthe mirror exchange is mounted on the collector mirror supporting base161 and moved along the mirror exchanging rail 162 in the forwarddirection of the collector mirror 10 (in the right direction in thedrawing) to be returned to a former position. Thereby, mirror exchangingcan be carried out safely and easily even for a heavy collector mirrorunit 130.

FIG. 3 is a plan view showing a positional relationship among thecollector mirror unit 130, the plasma generating point, and the focusingpoint. The collector mirror unit 130 is preferably moved in a backwardside (left side area in the drawing) of a plane shown by a broken lineIII-III (a plane which is perpendicular to an axis including the plasmagenerating point and the focusing point, and includes the plasmagenerating point). This is because units such as the target nozzle 110,the EUV filter 140, the target collecting unit 150 etc. (refer toFIG. 1) are disposed in the forward side of the collector mirror 10, andthe collector mirror unit 130 need to be prevented from interfering withthese units in the mirror exchanging operation. Specifically, as shownby arrows in FIG. 3, the collector mirror unit 130 is moved backward(left direction in the drawing), sideways (upward or downward directionin the drawing), or upward or downward (direction out of or into thedrawing) such that a moving path of the collector mirror unit 130 doesnot cross the above-mentioned plane including the plasma generatingpoint.

Although the collector mirror unit 130 is moved backward in the presentembodiment, in the case where the collector mirror unit 130 is moved inanother direction, the collector mirror unit 130 may be moved along themirror exchanging rail 162 after the position adjusting stage 163 hasbeen rotated by a desired angle (90 degrees or less), for example.

Further, as guiding means for guiding the collector mirror unit 130, themirror exchanging rail 162 is provided to the side of the collectormirror exchanging apparatus 160 in the present embodiment, however, themirror exchanging rail 162 may be provided to the side of the collectormirror unit 130 or a groove may be formed on the side of the collectormirror unit 130 so that a moving direction of the collector mirror unit130 is regulated.

Next, a collector mirror exchanging apparatus according to a secondembodiment of the present invention will be described with reference toFIG. 4. FIG. 4 is a side view showing the collector mirror exchangingapparatus according to the present embodiment and a collector mirrorunit mounted thereon. Also, FIG. 4 shows a chamber isolating wall 100 ofan EUV light source apparatus in which the collector mirror exchangingapparatus is used.

The collector mirror exchanging apparatus shown in FIG. 4 furtherincludes a mirror carrier 210, a mirror reversing unit 211, a mirrorexchanging rail 212, and a mirror carrier fixing unit 213, in additionto the collector mirror exchanging apparatus 160 shown in FIG. 1.

The mirror carrier 210 is a carriage used for carrying the collectormirror unit 130. Also, the mirror reversing unit 211 has a rotatingstage which rotates in the horizontal plane and reverses a direction ofthe corrector mirror unit 130 by rotating the rotating stage mountingthe collector mirror unit 130 thereon. On the mirror carrier 210 and themirror reversing unit 211, the mirror exchanging rail 212 is disposed asa guide to be used when the collector mirror unit 130 is moved. Also,the mirror carrier fixing unit 213 fixes the mirror carrier 210 to acollector mirror supporting base 161 via the mirror reversing unit 211.

These units 210 to 213 are used by being inserted into a chamber througha mirror access 101 provided on the chamber isolating wall 100 in therear side of the collector mirror unit 130, when the collector mirrorunit 130 is exchanged. At this time, a part of the mirror reversing unit211 is inserted into the chamber and a carriage part of the mirrorcarrier 210 is made to wait outside the chamber (in the left side of thechamber isolating wall 100). Alternatively, when the collector mirrorunit 130 is disposed at a back of a vacuum chamber, the carriage part ofthe mirror carrier 210 may be moved close to the chamber isolating wall100 to insert the mirror reversing unit 211 further into the back suchthat a protruded part of the mirror exchanging rail 212 on the mirrorcarrier 210 enters into the chamber, for example. Although the mirroraccess 101 is shown in an open state in FIG. 4, the mirror access 101 isusually closed by a mirror exchanging hatch during generation of EUVlight.

A collector mirror exchanging method according to the present embodimentwill be described with reference to FIGS. 4 and 5.

First, a pressure and an atmosphere within the chamber is set to be anitrogen atmosphere with a pressure the same as or a slightly higher(positive pressure) than an outside air pressure. Next, the mirrorexchanging hatch provided on the chamber isolating wall 100 is opened.Then, the mirror reversing unit 211 is inserted through the openedmirror access 101, and fixed to the collector mirror supporting base 161by using the mirror fixing unit 213. Thereby, the mirror exchanging rail162 on the collector mirror supporting base 161 and the mirrorexchanging rail 212 on the mirror reversing unit 211 and the mirrorcarrier 210 are coupled substantially in a straight line and a directionin which the collector mirror unit 130 is to be moved is determined.

Next, a lock of an alignment fixing unit on the collector mirrorsupporting base 161 is released to enable the collector mirror unit 130to be moved. Then, the collector mirror unit 130 is moved along themirror exchanging rails 162 and 212 onto the mirror reversing unit 211.

Next, as shown in FIG. 5, the stage of the mirror reversing unit 211 isrotated by 180 degrees to reverse the direction of the collector mirrorunit 130. In a state in which a collector mirror 10 faces outside of thechamber in this manner, the used collector mirror 10 is removed from thecollector mirror unit 130 and a new collector mirror 10 is attached.

Next, the stage of the mirror reversing unit 211 is rotated by 180degrees to make the collector mirror 10 face inside the chamber. Then,the collector mirror unit 130 is moved along the mirror exchanging rails212 and 162 to a position where the collector mirror unit 130 strikes analignment pin 164. Further, the alignment fixing unit on the collectormirror fixing base 161 is locked. Lastly, the mirror exchanging hatch isclosed and a collector mirror exchanging operation is completed. At thisstage, the collector mirror unit 130 is in a rough alignment at thisstage, and an accurate alignment is further to be carried out before EUVlight generation is started again.

Here, as described hereinabove, pipes 21 and 22 provided to a coolingunit 20 of the collector mirror unit 130 are made of a flexible materialand the movement and rotation of the collector mirror unit 130 can becarried out smoothly. However, in order to carry out more smoothrotation or the like of the collector mirror unit 130, the rotation orthe like of the collector mirror unit 130 may be carried out after thepipes 21 and 22 are removed.

Also, while only a collector mirror 10 is exchanged in the presentembodiment, the whole collector mirror unit 130 may be exchanged for anew one. At this time, another collector mirror unit 130 attached with anew collector mirror 10 and mounted on another mirror carrier 210 may beprepared for carrying out a collector mirror exchanging operationquickly.

In this case, an exchanging operation is carried out as follows. A usedcollector mirror unit 130 is mounted on a mirror carrier 210, and then,the mirror carrier 210 is moved after the mirror carrier fixing unit 213has been released, and in exchange, another mirror carrier 210 having anew collector mirror unit 130 thereon is fixed to the collector mirrorsupporting base 161 to move the collector mirror unit 130 into thechamber. In this case, the pipes 21 and 22 may be shifted from the usedcollector mirror unit 130 to the new collector mirror unit 130 at anytiming, however, the shift may be carried out more smoothly outside thechamber.

Next, a collector mirror exchanging apparatus according to a thirdembodiment of the present invention will be described with reference toFIG. 6. FIG. 6 is a side view showing the collector mirror exchangingapparatus according to the present embodiment and a collector mirrorunit mounted thereon. Also, FIG. 6 shows a chamber isolating wall 100 ofan EUV light source apparatus in which the collector mirror exchangingapparatus is used.

The collector mirror exchanging apparatus shown in FIG. 6 furtherincludes a mirror carrier 310, a mirror rotating unit 311 having arotating axis perpendicular to the drawing, an elevator stage 312, acoupling stage 313, a mirror exchanging rail 314, and a mirror carrierfixing unit 315, in addition to the collector mirror exchangingapparatus 160 shown in FIG. 1.

The mirror carrier 310 is a carriage to be used for carrying a collectormirror unit 130. Also, the mirror rotating unit 311 and the elevatorstage 312 are units for rotating the collector mirror unit 130 mountedon the coupling stage 313 within the vertical plane to change thedirection of the collector mirror unit 130. Further, the coupling stage313 is a stage for coupling the elevator stage 312 and the collectormirror supporting base 161, and a part thereof is inserted into achamber through a mirror access 101 provided on the chamber isolatingwall 100 when a collector mirror is exchanged. On these elevator stage312 and coupling stage 313, the mirror exchanging rail 314 to be used asa guide for moving the collector mirror unit 130 is disposed. Also, themirror carrier fixing unit 315 fixes the mirror carrier 310 to thecollector mirror supporting base 161 via the coupling stage 313.

A collector mirror exchanging method according to the present embodimentwill be described with reference to FIGS. 6 and 7.

In the present embodiment, the collector mirror unit 130 is rotatedwithin the vertical plane by about 90 degrees by using the mirrorrotating unit 311 and the elevator stage 312, instead of being rotatedwithin the horizontal plane to change a direction thereof (secondembodiment).

Thereby, a reflecting surface of the collector mirror 10 faces upward asshown in FIG. 7, and the collector mirror 10 is exchanged in this state.Since the collector mirror 10 has a heavy weight, when the collectormirror 10 is made to face upward, a mirror exchanging operation and thefollowing positioning operation to position the collector mirror 10against a collector mirror fixing unit 12 (FIG. 2) can be carried outeasily. Other exchanging sequences are similar to those in the secondembodiment.

Next, a collector mirror exchanging apparatus according to a fourthembodiment of the present invention will be described with reference toFIGS. 8A to 9. FIG. 8A is a rear view showing an EUV light sourceapparatus in which the collector mirror exchanging apparatus accordingto the present embodiment is provided, and FIG. 8B is a side viewshowing a part of the EUV light source apparatus. Also, FIG. 9 is anenlarged plan view showing the EUV light source apparatus shown in FIGS.8A and 8B.

The EUV light source apparatus shown in FIGS. 8A to 9 is provided with alaser unit 400 to be used for a collector mirror alignment outside achamber (left side of a chamber isolating wall 100). An opening isformed in the center of a collector mirror unit 130 for transmitting alaser beam 404 for alignment. Further, a mirror exchanging hatch 102 isprovided on the chamber isolating wall 100 in the rear side of thecollector mirror unit 130, and an alignment window 103 is provided atthe center thereof. A part of this window 103 is made of a material totransmit the laser beam 404 for alignment therethrough. Although asliding type mirror exchanging hatch 102 is shown in FIGS. 8A and 8B,another type of hatch may be used for opening and closing the hatch, ifa space allows therefor.

As shown in FIG. 9, the alignment laser unit 400 includes a helium(He)-neon (Ne) laser 401 and reflecting mirrors 402 and 403. Positionsand directions of these reflecting mirrors 402 and 403 are set such thata laser beam 404 output from the He—Ne laser 401 transmits the alignmentwindow 103 and passes through the center opening of the collector mirrorunit 130.

The collector mirror exchanging apparatus according to the presentembodiment has a structure to accommodate the case where such analignment laser unit 400 is provided. That is, as shown in FIG. 9, thiscollector mirror exchanging apparatus includes a mirror exchanging guidestage 410, a mirror carrier 420, and a collector mirror supporting base161 which is disposed inside the chamber isolating wall. The collectormirror supporting base 161 is provided with a mirror exchanging rail 162and an alignment pin 164.

The mirror exchanging guide stage 410 is a movable stage to be used whenthe collector mirror unit 130 is taken out of the chamber, and on theupper surface thereof, there are provided a drawing guide 411 to be usedwhen the collector mirror unit 130 is drawn backward out of the chamber,and a sliding guide 412 for preventing the collector mirror unit 130from falling and to be used when the collector mirror unit 130 is slidto a lateral side.

Meanwhile, the mirror carrier 420 is a carriage for carrying thecollector mirror unit 130. The mirror carrier 420 is provided with acoupling guide 421 for coupling to the mirror exchanging guide stage410, a sliding guide 422 to be used when the collector mirror unit 130is slid, and a guide 423 for preventing the collector mirror unit 130from falling.

Next, a collector mirror exchanging method according to the presentembodiment will be described with reference to FIGS. 9 to 14.

First, as shown in FIG. 9, a pressure and an atmosphere within thechamber is set to be a nitrogen gas with a pressure the same as or aslightly higher (positive pressure) than that of outside air. Also, amirror carrier 420 is prepared near the chamber.

Next, as shown in FIG. 10, the mirror exchanging hatch 102 is opened,and the mirror exchanging guide stage 410 is slid and inserted into thechamber to be fixed to the collector mirror supporting base 161.Thereby, the mirror exchanging rail 162 on the collector mirrorsupporting base 161 and the drawing guide 411 on the mirror exchangingguide stage 410 are coupled substantially in a straight line and adirection in which the collector mirror unit 130 is moved is determined.

Next, a lock of an alignment fixing unit on the collector mirrorsupporting base 161 is released to enable the collector mirror unit 130to be moved. Then, as shown in FIG. 11, the collector mirror unit 130 ismoved along the mirror exchanging rail 162 and the drawing guide 411 toa position near a rear end of the mirror exchanging guide stage 410.Then, pipes 21 and 22 connected to the collector mirror unit 130 areremoved.

Next, as shown in FIG. 12, the mirror exchanging guide stage 410 isdrawn out from the chamber together with the whole collector mirror unit130. Then, the coupling guide 421 of the mirror carrier 420bridge-connects the mirror exchanging guide stage 410 to couple themirror carrier 420 to the mirror exchanging guide stage 410. Next, asshown in FIG. 13, the collector mirror unit 130 is moved along thesliding guides 412 and 422 to the mirror carrier 420, and then, as shownin FIG. 14, the collector mirror unit 130 mounted on the mirror carrier420 is carried.

Next, a used collector mirror 10 is exchanged for a new collector mirror10 at a destination of the collector mirror unit 130. Alternatively, thewhole collector mirror unit 130 may be exchanged for a new one. Then,the collector mirror unit 130 is moved in the reverse sequence of takingout the collector mirror unit 130, and disposed within the chamber afterthe pipes 21 and 22 having been connected. Thereby, a collector mirrorexchanging operation is completed. At this stage, the collector mirror10 is in a rough alignment and an accurate alignment is further to becarried out.

While, in the present embodiment, a moving direction of the collectormirror is changed (backward to sideways) in this manner, a moving pathof the collector mirror unit does not cross a plane including a plasmagenerating point (plane shown by a broken line III-III in FIG. 3) ineither direction. Therefore, the collector mirror unit can be exchangedsmoothly without interfering with the units disposed within the chamber.

Also, in the present embodiment, another mirror carrier on which a newcollector mirror unit 130 is mounted may be preliminarily prepared.Thereby, it becomes possible to carry out a collector mirror exchangingoperation further efficiently.

Next, a collector mirror exchanging apparatus and exchanging methodaccording to a fifth embodiment of the present invention will bedescribed with reference to FIG. 15. FIG. 15 is a plan view showing apart of an EUV light source apparatus in which the collector mirrorexchanging apparatus according to the present embodiment is provided.

As shown in FIG. 15, in the case where a space for maintenance isobtained in a lateral side (downward in the drawing) of a collectormirror unit 130, the collector mirror unit 130 may be drawn out to thelateral side for exchanging a collector mirror.

In this case, on a collector mirror supporting base 500 which supportsthe collector mirror unit 130 within a chamber, there are disposed amirror exchanging rail 501 to be used as a guide when the collectormirror unit 130 is moved sideways and an alignment pin 502 whichdetermines a stop position of the collector mirror unit 130 in asideways direction thereof. Also, a mirror carrier 510, which isprovided with a coupling guide 511, a sliding guide 512, and a fallprevention guide 513, is used as a carriage for carrying the collectormirror unit 130.

When a collector mirror is exchanged, a mirror exchanging hatch 104provided on a lateral side of the collector mirror unit 130 is openedand the mirror carrier 510 is inserted into the chamber through a mirroraccess 105. Then, the collector mirror unit 130 is moved along themirror exchanging rail 501 and the sliding guide 512 onto the mirrorcarrier 510, and the collector mirror unit 130 mounted on the mirrorcarrier 510 is drawn out of the chamber. Further, a collector mirror 10is exchanged for a new one, and the collector mirror unit is attachedagain within the chamber in the reverse sequence. Alternatively, thewhole collector mirror unit 130 may be exchanged for a new one.

According to the present embodiment, even in the case where an alignmentlaser unit 400 is disposed on the rear side of the collector mirror unit130, a collector mirror exchanging operation can be carried out withoutconsideration of an interference with the unit 400.

Although, in the present invention, the collector mirror 10 is exchangedin a state in which the collector mirror unit 130 is just slid out, thecollector mirror 10 may be exchanged after the direction of thecollector mirror unit 130 has been changed, if required. In this case, amechanism for rotating the collector mirror unit 130 may be provided tothe mirror carrier 510, as described in the second and thirdembodiments.

Next, a collector mirror exchanging apparatus and exchanging methodaccording to a sixth embodiment of the present invention will bedescribed with reference to FIGS. 16 to 18. FIGS. 16 to 18 are sideviews showing a part of an EUV light source apparatus in which thecollector mirror exchanging apparatus according to the presentembodiment is provided.

As shown in FIG. 16, in the case where a space for maintenance can beobtained in the upper side of a collector mirror unit 130 (upward in thedrawing), a collector mirror may be exchanged by drawing out thecollector mirror unit 130 upward.

In this case, a collector mirror supporting base 600 for supporting thecollector mirror unit 130 and an elevator guide 601 are provided with ina chamber. The collector mirror supporting base 600 is disposed so as togo up or down along the elevator guide 601. Also, the collector mirrorsupporting base 600 is attached to the elevator guide 601 via a rotatingjig 602. The rotating jig 602 has a rotating axis perpendicular to thedrawing.

When a collector mirror is exchanged, as shown in FIG. 16, a mirrorexchanging hatch 106, which is provided above the collector mirror unit130, is opened. Then, as shown in FIG. 17, the collector mirrorsupporting base 600 is lifted along the elevator guide 601, and thecollector mirror unit 130 is taken out through a mirror access 107.Further, as shown in FIG. 18, the collector mirror supporting base 600is rotated by about 90 degrees and the reflecting surface of a collectormirror 10 is made to face upward. In this state, the collector mirror 10is exchanged for a new one. After that, the collector mirror unit 130 isattached again within the chamber in the reverse sequence.

According to the present embodiment, even in the case where an alignmentlaser unit 400 is disposed on the rear side of the collector mirror unit130, a collector mirror exchanging operation can be carried out withouta consideration of an interference with the unit 400.

Although the collector mirror 10 is exchanged in a state reflectingsurface thereof is made to face upward in the present embodiment, themirror may be exchanged in a state the surface thereof continues to facesideways. In this case, the rotating jig 602 may not be provided.

Although, in the first to sixth embodiments described hereinabove, astructure (collector mirror unit) including a collector mirror with acooling unit and a rotating unit is used, the present invention may beapplied to the case where a structure not including a peripheralmechanism of a collector mirror is exchanged, that is, the case whereonly a collector mirror or a structure including a collector mirror andonly a supporting mechanism thereof is exchanged.

1. A collector mirror exchanging apparatus to be used for exchanging acollector mirror, which reflects and collects extreme ultra violet lightemitted from plasma generated within a chamber of an extreme ultraviolet light source apparatus, said collector mirror exchangingapparatus comprising: a supporting base which supports one of acollector mirror and a collector mirror structure including saidcollector mirror; and guiding means disposed on said supporting base andregulating a moving direction of said one of said collector mirror andsaid collector mirror structure; wherein at least said collector mirroris taken out of said chamber by moving said one of said collector mirrorand said collector mirror structure along said guiding means on saidsupporting base.
 2. The collector mirror exchanging apparatus accordingto claim 1, wherein said guiding means is disposed at a position notcrossing a plane which is perpendicular to an axis including a plasmagenerating point within said chamber and a focusing point of extremeultra violet light by said collector mirror and which includes theplasma generating point.
 3. The collector mirror exchanging apparatusaccording to claim 1, further comprising: a carriage which carries saidone of said collector mirror and said collector mirror structure andincludes a coupling mechanism to be coupled to said supporting base andsecond guiding means disposed on said coupling mechanism, wherein saidsecond guiding means is coupled continuously to said guiding meansdisposed on said supporting base when said carriage is coupled to saidsupporting base.
 4. The collector mirror exchanging apparatus accordingto claim 3, wherein said carriage further includes a rotating mechanismwhich changes a direction of said one of said collector mirror and saidcollector mirror structure when said one of said collector mirror andsaid collector mirror structure is mounted thereon.
 5. A collectormirror exchanging apparatus to be used for exchanging a collectormirror, which reflects and collects extreme ultra violet light emittedfrom plasma generated within a chamber of an extreme ultra violet lightsource apparatus, said collector mirror exchanging apparatus comprising:a collector mirror structure including a collector mirror; guiding meansprovided to said collector mirror structure and regulating a movingdirection of said collector mirror structure; and a supporting basewhich supports said collector mirror structure; wherein said collectormirror structure is taken out of said chamber by moving said collectormirror structure along said guiding means on said supporting base.
 6. Acollector mirror exchanging method of exchanging a collector mirror,which reflects and collects extreme ultraviolet light emitted fromplasma generated within a chamber of an extreme ultra violet lightsource apparatus, said method comprising the steps of: (a) moving one ofa collector mirror and a collector mirror structure including saidcollector mirror while regulating a moving direction thereof alongguiding means disposed on a supporting base, to take at least saidcollector mirror out of said chamber; (b) exchanging a used collectormirror for a new collector mirror outside said chamber; and (c) movingone of said collector mirror after exchange and said collector mirrorstructure including said collector mirror after exchange whileregulating a moving direction thereof along said guiding means disposedon said supporting base, to return at least said collector mirror to aformer position thereof.
 7. The collector mirror exchanging methodaccording to claim 6, wherein said guiding means is disposed at aposition not crossing a plane which is perpendicular to an axisincluding a plasma generating point within said chamber and a focusingpoint of extreme ultra violet light by said collector mirror and whichincludes the plasma generating point.
 8. The collector mirror exchangingmethod according to claim 6, wherein each of step (a) and step (c)includes coupling a carriage, which carries said one of said collectormirror and said collector mirror structure and includes a couplingmechanism to be coupled to said supporting base and second guiding meansdisposed on said coupling mechanism, to said supporting base, therebycoupling said second guiding means continuously to said guiding meansdisposed on said supporting base and moving said one of said collectormirror and said collector mirror structure on said supporting base andsaid carriage.
 9. The collector mirror exchanging method according toclaim 8, further comprising the steps of: changing, prior to step (b), adirection of said one of said collector mirror and said collector mirrorstructure mounted on said carriage; and restoring, after step (b), thedirection of said one of said collector mirror and said collector mirrorstructure mounted on said carriage to a former direction thereof.
 10. Acollector mirror exchanging method of exchanging a collector mirror,which reflects and collects extreme ultraviolet light emitted fromplasma generated within a chamber of an extreme ultra violet lightsource apparatus, said method comprising the steps of: (a) moving acollector mirror structure including a collector mirror while regulatinga moving direction thereof along guiding means provided to saidcollector mirror structure on said supporting base, to take saidcollector mirror structure out of said chamber; (b) exchanging a usedcollector mirror for a new collector mirror outside said chamber; and(c) moving said collector mirror structure including said collectormirror after exchange while regulating a moving direction thereof alongsaid guiding means on said supporting base, to return said collectormirror structure to a former position thereof.